Concept:
This question requires converting an imperative sentence combined with a conditional clause from direct speech into indirect (reported) speech.
Key rules for converting imperative speech containing counsel or guidance:
• Reporting Verb Modification: The phrase "said to" changes based on the tone of the sentence. Since a teacher guiding students on how to succeed is offering helpful guidance, the reporting verb changes to "advised".
• Infinitive Construction: The imperative mood of the original verb ("Work hard") is converted into an infinitive phrase: "to work hard".
• Tense and Pronoun Shifting:
• The second-person pronoun "you" shifts to match the object ("the boys"), converting it to the third-person plural pronoun "they".
• The simple present verb "want" shifts back into the simple past tense form, "wanted".
Step 1: {Evaluating each option systematically.}
Let us analyze how each option handles these reporting transformations:
• The teacher told the boys...: Using "told" is too neutral and completely misses the supportive, guiding tone of the teacher's statement.
• The teacher advised the boys to work hard if they wanted to pass.: This perfectly applies the reporting verb "advised," correctly connects the infinitive phrase "to work hard," switches the pronoun to "they," and changes the verb to the past tense "wanted."
• The teacher ordered the boys...: The phrase "ordered" implies a strict, disciplinary command, which does not fit the encouraging conditional clause ("if you want to pass").
• The teacher asked the boys...: "Asked" is primarily used for interrogative questions or simple requests, making it incorrect for this piece of advice.
Step 2: {Final structural synthesis.}
Option (2) perfectly captures both the grammar mechanics and the supportive tone of the original spoken sentence.